1. Field of the Invention
The present invention relates to substrate structures and fabrication methods thereof, and more particularly, to a substrate structure and a fabrication method thereof for reducing thermal warping.
2. Description of Related Art
Along with the rapid development of electronic industries, electronic products are required to be reduced in thickness, and accordingly thin type substrates are needed.
FIGS. 1A to 1G are schematic cross-sectional views showing a method for fabricating a substrate structure according to the prior art.
Referring to FIG. 1A, a carrier 10 is provided and a seed layer 11 is formed on opposite surfaces of the carrier 10.
Referring to FIG. 1B, a patterned resist layer 12 having a plurality of openings is formed on the seed layer 11. Thereafter, a first circuit layer 13 is formed in the openings of the patterned resist layer 12 by electroplating.
Referring to FIG. 1C, the patterned resist layer 12 is removed.
Referring to FIG. 1D, a dielectric layer 14 is formed on the carrier 10 and the first circuit layer 13.
Referring to FIG. 1E, a plurality of openings are formed in the dielectric layer 14. Then, a second circuit layer 15 is formed on the dielectric layer 14, and a plurality of conductive vias 15a are formed in the openings of the dielectric layer 14 and electrically connecting the first circuit layer 13 and the second circuit layer 15.
Referring to FIG. 1F, the carrier 10 and the seed layer 11 are removed to expose the first circuit layer 13.
Referring to FIG. 1G an insulating layer 16 made of, for example, solder mask is formed on opposite surfaces of the dielectric layer 14. As such, a substrate structure 1 is obtained.
Through the above-described method, a thin type substrate structure is obtained. However, when the substrate structure is bonded with a chip and subjected to a molding process for forming a package structure, thermal warping easily occurs to the substrate structure. On the other hand, the molding compound generally has a thickness too small (for example, less than 0.5 mm) to overcome or balance thermal warping stresses, thus leading to warping of the overall package structure.
Therefore, there is a need to provide a substrate structure and a fabrication method thereof so as to overcome the above-described drawbacks.